1. Field of the Invention
This invention relates in general to an improvement in an engine valve such as an intake or exhaust valve of an internal combustion engine, and more particularly to the engine valve which is hollow for the purpose of weight reduction.
2. Description of the Prior Art
It is well known in the art, that engine valves such as intake and exhaust valves of internal combustion engines are in general formed solid and made of a heat-resistant material. Additionally, it has been proposed in the fields of air plane engines and racing car engines, that exhaust valves subjected to severe thermal condition are formed hollow and filled with sodium. However, either of the above engine valves has disadvantages in that the valve is relatively heavy and accordingly the inertial mass thereof during valve opening and closing operations becomes higher. This unavoidably results in increased engine noise and deteriorated fuel economy.